Rates of obesity and its co-morbidities are increasing alarmingly throughout the world due to a complex mix of dietary, environmental, and behavioral factors. Of great concern, 15% of 2?5-year-old children are obese. Significantly, emerging evidence indicates that the risk factors associated with obesity and other aspects of metabolic syndrome may exert their influence prenatally. Hyper-caloric intake of fat and nutritive sweeteners, such as high-fructose corn syrup, plays perhaps the most crucial detrimental role in this epidemic. However, avoidance of dietary sugar has become increasingly challenging as it is frequently added to all types of food. Our group has focused on the fructose component of sugar in the pathogenesis of metabolic disease and are actively involved in the identification of modifiable biological factors involved in sugar-induced metabolic syndrome (MetS). Among these potential targets, we have identified the enzyme fructokinase (Khk), which catalyzes the first step in conversion of fructose into fat and calories, as a potential candidate to slow the progression of MetS induced by sugar. Importantly, our pilot data indicate that at weaning, offspring from fructose-fed Khk-knockout (Khk-KO), but not wild-type, dams have significantly reduced risk of developing MetS even if pups carry functional Khk loci and can metabolize sugar. Our preliminary data also suggest that protection against MetS in the offspring of Khk-KO mice may occur through mother-to-infant transfer of obesity-resistant microbiota in the perinatal period. These observations have prompted our overall hypothesis that Khk blockade could be a clinically relevant therapeutic approach for the prevention and treatment of childhood metabolic disease. The proposed Specific Aims innovatively integrate metagenomic, pathophysiological, cellular, and molecular studies using innovative murine models to address several fundamental issues related to how gene-diet-microbiota interactions influence obesity pathogenesis: Aim 1) Determine the contributions of maternal and fetal fructokinase activity to prenatal programming of sugar-induced metabolic dysfunction in offspring and Aim 2) Determine the role of maternal sugar consumption in postnatal programming of offspring metabolic dysfunction. Impact: This study will provide novel insight into the mechanisms by which dietary sugar, a harmful component of the western diet, disrupts maternal, fetal, and neonatal metabolic homeostasis. Completion of these Aims will provide critical pre-clinical data concerning the therapeutic efficacy of Khk inhibition in combating childhood obesity and metabolic disease. Moreover, identifying host and microbial factors that protect mice from the pathological effects of excessive dietary fructose ? for example microbial consortia or metabolic products that are enriched in metabolic disease-resistant Khk-KO animals ? may suggest novel means of preventing or treating metabolic disease.